CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Meshing & Mesh Conversion

[snappyHexMesh] Edge/Surface snapping on thin geometry

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 14, 2012, 05:06
Default Edge/Surface snapping on thin geometry
  #1
New Member
 
Tom
Join Date: Mar 2011
Posts: 11
Rep Power: 15
tidal_Tom is on a distinguished road
I am trying to mesh a simple diffuser using SHM. I created the diffuser geometry as an STL file and used the surfaceFeatureExtract command. However, I am struggling to get SHM to snap to my geometry. See attached image of the diffuser surface mesh, and with the STL file showing corner edges it has missed. I have also attached the SHM dict and stl file.

Previously I have used Gmsh so am unfamiliar with the settings I need in SHM to achieve suitable snapping.

Any help/advice would be much appreciated.

Regards
Tom
Attached Images
File Type: jpg diffuser_Mesh.jpg (97.7 KB, 54 views)
File Type: jpg diffuser_Mesh_STL.jpg (97.5 KB, 55 views)
Attached Files
File Type: txt snappyHexMeshDict.txt (10.6 KB, 12 views)
File Type: txt blockMeshDict.txt (1.4 KB, 5 views)
File Type: zip diffuser.zip (78.5 KB, 3 views)
tidal_Tom is offline   Reply With Quote

Old   May 14, 2012, 05:30
Default
  #2
Senior Member
 
lore
Join Date: Mar 2010
Location: Italy
Posts: 460
Rep Power: 18
lovecraft22 is on a distinguished road
Send a message via Skype™ to lovecraft22
Hi Tom;
have you run surfaceFeatureExtract?
If you did, with which flags?

Should be something like this:

Quote:
surfaceFeatureExtract -includedAngle 150 -writeObj constant/triSurface/diffuser.stl diffuser
lovecraft22 is offline   Reply With Quote

Old   May 14, 2012, 05:36
Default
  #3
New Member
 
Tom
Join Date: Mar 2011
Posts: 11
Rep Power: 15
tidal_Tom is on a distinguished road
Wow, thank you for your quick reply.

Yes I used that exact command and checked the resulting object file to see the edges that were extracted were correct, which they were.

The problem seems to be with SHM in getting the mesh to snap to those edges.
tidal_Tom is offline   Reply With Quote

Old   May 14, 2012, 06:23
Default
  #4
Senior Member
 
lore
Join Date: Mar 2010
Location: Italy
Posts: 460
Rep Power: 18
lovecraft22 is on a distinguished road
Send a message via Skype™ to lovecraft22
Don't know exactly what's causing the issue here. I started sHM with the motorbike dictionary and I managed to get it working ok. If compared to your dictionary a lot of stuff is different…
To speed up the process I removed the layers and decreased the mesh refinement on the diffuser…

You may want to run

Quote:
diff my_sHMDict your_sHMDict
to find the differences between the two.


Hope this helps…

Regards
Attached Files
File Type: zip snappyHexMeshDict.zip (4.2 KB, 17 views)
lovecraft22 is offline   Reply With Quote

Old   May 14, 2012, 07:32
Default
  #5
New Member
 
Tom
Join Date: Mar 2011
Posts: 11
Rep Power: 15
tidal_Tom is on a distinguished road
Brilliant, thank you very much.

After increasing the refinement 1 more level all edges are snapped and well defined.

After some playing I think the parameter that had the biggest effect was the 'resolveFeatureAngle'. Previously I had 90, but in your dictionary 30 and this improved the snapping a lot.

Thanks again for your help,

Tom
tidal_Tom is offline   Reply With Quote

Reply

Tags
edge, snapping, snappyhexmesh


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[snappyHexMesh] SnappyHexMesh : snapping not matching surface Awak OpenFOAM Meshing & Mesh Conversion 4 May 31, 2016 08:23
Import Deformed Geometry into Fluent lgamble FLUENT 1 February 25, 2016 13:59
[snappyHexMesh] SHM not snapping to some surfaces Swift OpenFOAM Meshing & Mesh Conversion 13 January 4, 2016 01:56
Problematic Geometry fatb0y CFX 15 October 13, 2010 17:17
vitual _ real deneb FLUENT 3 January 22, 2007 04:31


All times are GMT -4. The time now is 00:52.